I have both Valentine 1 and passport 8500. Both work very well. Val 1 is a bit more sensitive so it picks up a lot of crap.. but i dont mind because when it does pick up k band it does it very well. Both have saved my butt time and time again so it is worth the investment. Just watch out for state troopers or big city cops. If they pop you with Ka or laser then you are kind of screwed because they tend to do it at very close range so there are no early warnings.. k band is not an issue in many cases. Another tip is to look at which software and hardware the val 1 is running.
http://en.wikipedia.org/wiki/Valentine_One